It is conventional to radiate primary light having a predefined primary light wavelength (e.g. blue “primary” light) onto a wavelength-converting phosphor body, by which the primary light is at least partly converted into light having a higher wavelength (e.g. into yellow “secondary” light) and is emitted again. The phosphor body may be for example a ceramic body composed of rare-earth-doped ceramic having a garnet structure and be adhesively bonded by silicone adhesive for thermal and mechanical linking on a carrier. If the primary light is laser light and if the phosphor body is spaced apart from the laser generating the primary light, this is also referred to as an LARP (“Laser Activated Remote Phosphor”) arrangement. In the case of the LARP arrangement, a (deflection) reflector is often provided in a primary light path between the laser and the phosphor body in order to deflect the primary light onto the phosphor body.
In this case, a homogenization of a density distribution of a radiation power or a radiation intensity of the primary light beam for an LARP application is worthwhile with regard to a photometric power and a lifetime. This applies e.g. to the case where organic materials are used in the laser beam path, for example the silicone adhesive for fixing the phosphor body. In the case of local peak values of the radiation intensity of a blue laser light beam of above 100 W/mm2, it has been found, for example, that the stability of commercially available silicone-based adhesives is exceeded for a lifetime that is sufficient in practice.
In order to reduce the peak values of the power density or the radiation intensity of the laser light beam, optical transmitted-light elements such as an integrator or a fly's eye lens can be introduced into the beam path of the laser light beam upstream of the phosphor body. However, a homogenization achievable in this way may still not suffice.